The present invention relates generally to fencing, particularly modular fencing components constructed of molded plastic material. More specifically, the invention relates to capping arrangements for plastic fence posts and the like.
The use of plastics for fencing components is known, e.g., in the agricultural, residential and home improvement industries. Plastics present a desirable alternative to wood as a construction material for fencing. Plastic fencing can take on the natural attractive appearance of wood while exhibiting superior durability. For example, vinyl fencing is highly resistant to the elements and does not require painting. Furthermore, modular plastic fencing components are less expensive to mass produce and easier to assemble than their wood counterparts.
Known plastic fencing constructions are disclosed in Pettit U.S. Pat. No. 4,722,514 and Simpson et al. U.S. Pat. No. 5,078,367. In these constructions, open ended tubular plastic fence posts are covered with decorative and protective molded plastic caps. In Pettit, ribs are formed on the inside surfaces of the bottom portions of the fence caps. The fence caps fit over the posts. The caps, ribs, and posts are dimensioned so that the caps will be held in position with a friction fit. Similarly, Simpson et al. disclose a cap that is friction fit over the end of a fence post. In this design, side walls of the post are friction fit between flanges provided in pairs along the inside perimeter of the fence cap.
The friction fit cap arrangements described above have certain deficiencies. Manufacturing tolerances may result in a friction fit that is too tight or too loose. If the friction fit is too tight, then the caps are difficult or impossible to properly install. If the friction fit is too loose, the cap is not securely held in place and may inadvertently be knocked off. Additionally, repeated removal and replacement of a friction fit cap will, due to wear, lead to loosening of the cap.
An arrangement that partially alleviates the above described problem is shown in German patent No. DE 3440-160-A. Therein, a decorative fence has a cap that is secured to a fence post by a snap tab attached to the cap and extending outwardly into a hole extending through the post sidewall. While this arrangement provides improved retention over the friction fit arrangements described above, the cap is still susceptible to easy removal, e.g., by vandals or thieves, by depression of the exposed tab end. Additionally, the through hole and exposed snap tab therein detract from the appearance of the fence.
It is also known in the art to secure a plastic cap to a plastic fence post using adhesive or known mechanical fasteners such as screws or rivets. These approaches have the obvious disadvantage that a labor intensive operation is required. Furthermore, a good bond by adhesive requires a high degree of surface contact between the mating parts. This may be difficult to consistently attain given the variations in typical plastic molding processes. Additionally, when screws or rivets are applied, care must be exercised to avoid stripping or breaking away the vinyl material, or the means of mechanical bonding will be lost.